Fibrinogen is a glycoprotein present as a normal component of blood plasma. It participates in platelet aggregation and fibrin formation in the blood clotting mechanism.
Platelets are cellular elements found in whole blood which also participate in blood coagulation. Fibrinogen binding to platelets is important to normal platelet function in the blood coagulation mechanism. When a blood vessel receives an injury, the platelets binding to fibrinogen will initiate aggregation and form a thrombus. Interaction of fibrinogen with platelets occurs through a membrane glycoprotein complex, known as GP IIb/IIIa; this is an important feature of the platelet function. Inhibitors of this interaction are useful in modulating platelet thrombus formation.
It is also known that another large glycoprotein named fibronectin, which is a major extracellular matrix protein, interacts with platelets. Various relatively large polypeptide fragments in the cell-binding domain of fibronectin have been found to have cell-attachment activity. See U.S. Pat. Nos. 4,517,686; 4,589,881; and 4,661,111. Certain relatively short peptide fragments from the same molecule were found to promote cell attachment to a substrate when immobilized on the substrate or to inhibit attachment when in a solubilized or suspended form. See U.S. Pat. Nos. 4,578,079 and 4,614,517.
In U.S. Pat. No. 4,683,291, inhibition of platelet function is disclosed with synthetic peptides designed to be high affinity antagonists of fibrinogen binding to platelets. U.S. Pat. No. 4,857,508 discloses tetrapeptides having utility as inhibitors of platelet aggregation.
Other synthetic peptides and their use as inhibitors of fibrinogen binding to platelets are disclosed by Koczewiak et al., Biochem.23, 1767-1774 (1984); Plow et al., Proc. Natl. Acad. Sci. 82, 8057-8061 (1985); Ruggeri et al., Ibid. 83, 5708-5712 (1986); Ginsberg et al., J. Biol. Chem. 260 (7), 3931-3936 (1985); Haverstick et al., Blood 66 (4), 946-952 (1985); and Ruoslahti and Pierschbacher, Science 238, 491-497 (1987). Still other such inhibitory peptides are disclosed in European Patent Applications 275,748 and 298,820.
U.S. Pat. No. 4,899,313 discloses peptide mimetic compounds containing a guanidino group which are useful as platelet aggregation inhibitors.
European Patent Application 512,831 discloses piperidinylalkylazacycloalkanones which inhibit the binding of fibrinogen to blood platelets and therefore are useful for inhibiting the aggregation of blood platelets.
European Patent Application 503,548 discloses cyclic urea derivatives (imidazolones and triazolones) useful in inhibiting cellular interactions and are therefore useful for treating or preventing, thrombosis, embolisms and metastases.
European Patent Application 496,378 discloses amidinobiphenyl compounds which inhibit cell-cell and cell-matrix interaction and are thus useful for treating thrombosis, cerebrovascular diseases, pulmonary embolisms, myocardial infarction, arteriosclerosis, osteoporosis and tumour metastases.
WO 93/09795 discloses non-peptide RGD analogs having terminal guanidino and carboxyl functions spaced by a chain of 11 atoms, at least 5 of which are carbon atoms, and containing no sequence of .alpha.-amino acids which compounds inhibit platelet aggregation and are useful for the treatment of several pathological disorders.
European Patent Application 445,796 discloses acetic acid derivatives which have inhibitory action on the bonding of adhesive proteins to blood platelets, as well as on blood platelet aggregation and cell-cell adhesion.
European Patent Application 372,486 discloses N-acyl beta amino acid derivatives and their salts. The disclosed compounds are useful for inhibiting platelet aggregation in the treatment of thrombosis, stroke, myocardial infarction, inflammation, arteriosclerosis, and for inhibiting metastasis.
European Patent Application 381,033 discloses amidino or guanidinoaryl substituted alkanoic acid derivatives useful for the treatment of thrombosis, apoplexy, cardiac infarction, inflammation, arteriosclerosis and tumors.